I really enjoyed my stay at Mukarnas Pera. The service was great (the staff in the reception spoke very good English which is not common in Istanbul, and they were very helpful to accomodate any request I might have), the hotel was very nice and clean, the room was silent with very efficient air conditioning, and the location was great (just a 3 minute walk from Taksim Square). The breakfast buffet was plentiful and filling, with slight variations in what was offered from day to day. The hotel is located in a very central area, with lots of nice cafes, bars and restaurants in the surrounding blocks.
I would highly recommend staying at the Mukarnas Pera to anyone who is looking for a good hotel in that part of town. I would definitely consider staying there again if I return to Istanbul.